最小空间周期对连续相位板加工和性能的影响

Effects of Least Spatial Period on the Fabrication and Performance of Continuous Phase Plate

最小空间周期是连续位相板(CPP)设计和加工过程中的重要特征参数。根据惯性约束聚变大型激光驱动装置的需求,建立不同空间周期的CPP设计与分析方法,研究了不同最小空间周期对磁流变加工和焦斑性能的影响。结果表明,磁流变加工的去除函数尺寸直接与CPP的最小空间周期成线性关系,而加工去除量与最小空间周期的平方根成线性关系,最小周期越大,加工越容易,但加工量越大;焦斑整形性能受最小空间周期的影响小,能量集中度差异小于0.2%,但焦斑顶部均匀性随着最小空间周期变小而变好,5 mm最小周期CPP的焦斑顶部不均匀比15 mm的CPP小3.5%。因此,设计时应尽量减小最小空间周期,但选取的最小空间周期不能大于加工设备的约束条件。

Least spatial period is an important parameter for the design and fabrication of continuous phase plate（CPP）. Based on the requirement of laser facility for inertial confinement fusion, a method of design and analysis for CPP with different least spatial periods is built up. The effects of least spatial period on the fabrication and performance of continuous phase plate have been studied. The results show that the removal function size is linearly correlated to the least spatial period, and the relationship between the removal and the square root of least spatial period is about linear, so the fabrication with larger least spatial period should be easier because the CPP has more medium-high frequency, but it has more material to be removed. Moreover, the beam shaping performance of CPP is rarely influenced by the least spatial period, the difference of capacity usage ratio caused by different CPP is smaller than 0.2%. But the uniformity of top focal spot caused by CPP becomes more excellent when the least spatial period is minimized, the nonuniformity of least spatial period CCP of 5 mm is 3.5% less than that of 15 mm. So the selected least spatial period should be minimized, while it can’t exceed the ability of the fabricating equipment.